Methods to incorporate varicolored fragments of material in wall surfaces have been known. For example, U.S. Pat. No. 772,476 discloses a method of veneering artificial stone by depositing a layer of cement on the face of a block, sprinkling granular material thereon, tamping the granular material and smoothing the surface by rubbing or grinding the exposed granules.
U.S. Pat. No. 1,361,763 discloses a method of mixing foreign particle with a conventional plastic mixture, which is then applied directly to the surface to be covered.
U.S. Pat. No. 4,496,504 discloses a method of exposing aggregate in poured concrete panels by pouring wet concrete having a coarse aggregate content into a casting bed, lifting coarse aggregate to the surface with a rotating aggregate lifter and depositing a high concentration of the coarse aggregate in front of a screed roller, and compacting.
U.S. Pat. No. 5,339,589 produces an aggregate floor by applying a layer of a flexible compound to a concrete slab, applying fiber glass mesh to the flexible compound, applying dry aggregate to the mesh and compacting with a vibrating roller, then applying thereto a compacted composite cement, water and sand in the form of a viscous solution, and then compacting with a roller to force out excess cement and trapped air.
U.S. Pat. No. 5,794,401 discloses a method of resurfacing existing floors or substrates by cleaning the surface of the substrate and applying a seed material mixed with a cementitious self-leveling topping, then curing, then grinding the exposed cured surface, and then sealing.
U.S. Pat. Nos. 6,016,635 and 6,033,146 disclose methods for surface seeding or broadcasting particulate over the surfaces of poured concrete mixes while the top surfaces are still plastic.
The above methods either:
1. Do not form monolithic structures, or
2. Disperse the relatively expensive decorative aggregate throughout the entire structure thereby increasing cost, or
3. Require labor intensive hand seeding or broadcasting of the decorative aggregate, or
4. Require a labor intensive and hence costly grinding step.
A method without any of these disadvantages would reduce the cost and/or increase the durability of the structure by making the structure monolithic.
This invention is directed towards processes for producing durable and attractive decorative aggregate-containing cementitious surfaces that are an integral part of monolithic structures.
This invention is also directed towards processes that:
1. Can produce such surfaces at a much lower cost by not requiring hand seeding or broadcasting of decorative aggregate over the top of such surfaces during their manufacture.
2. Do not required decorative aggregate throughout the entire monolithic structure.
3. Do not require grinding the cured surfaces.
This invention can be used on monolithic structures having any strength desired and suitable for usage ranging from light pedestrian traffic on home patios to heavy vehicular traffic. This invention is intended for new monolithic structures in compliance with the least stringent specifications to the most stringent specifications depending only on the required duty that such monolithic structures are to serve. For example, this invention can produce monolithic structures having strength ratings of 2200 psi, 3000 psi, 4000 psi or higher if desired. Unless otherwise specified all psi strength rating referred herein are concrete compressive strengths at 28 days.
Accordingly, there is provided by the principles of this invention a process for producing a monolithic architectural cementitious structure having a decorative aggregate-containing cementitious surface comprising forming a freshly poured cementitious base. The cementitious base does not contain any decorative aggregate. With reference to FIG. 1, a compacted subgrade material 20 is preferably first laid on a rough graded site 21. Then reinforcing bar or rebar, or wire mesh 22 is set to reinforce the ultimately formed monolithic structure. Next a cementitious base 23 is produced and laid from suitable formulation having the strength properties required. Usually the decorative aggregate-containing cementitious portion of such structure is between 2% and 17% of the total thickness of monolithic architectural cementitious structure while the cementitious base is between 98% and 83% of said total thickness. In one embodiment, the freshly poured cementitious base 23 has a thickness of at least about 3 inches.
By the term xe2x80x9cdecorative aggregatexe2x80x9d as used herein is meant aggregate that is used to produce an attractive or architectural surface. The term xe2x80x9cdecorative aggregatexe2x80x9d as used herein is not meant to include any aggregate used for merely adding strength to the monolithic structure without also enhancing the beauty of the surface. For example, No. 4 aggregate, which is used in many concrete mixes for strength, is not a xe2x80x9cdecorative aggregatexe2x80x9d as that term is used herein. The appearance of decorative aggregate is not the same as the appearance of the aggregate in the cementitious base. Thus the aggregate used for adding strength to the cementitious base not the same as the decorative aggregate used for producing the attractive surfaces of this invention.
Since the decorative aggregate is relatively expensive material there is substantial cost savings in this process since the cementitious base does not contain the relatively expensive decorative aggregate. Furthermore, since the formulation of the decorative aggregate-containing cementitious slurry is relatively more expensive per unit volume than the formulation of the cementitious base per unit volume, the cost of producing the monolithic architectural cementitious structures with the decorative aggregate-containing surfaces is reduced when thickness of the decorative aggregate-containing cementitious layer is reduced. However, said thickness must be effective for securing and locking in the exposed decorative aggregate.
With reference to FIG. 2, this invention further comprises preparing a decorative aggregate-containing cementitious slurry 24 having at least decorative aggregate 26 and cementitious matrix composition 28 (also referred to herein as the decorative cementitious matrix blend) operable for forming a monolithic structure when applied to the freshly poured cementitious base and simultaneously cured therewith. In one embodiment of this invention, the cementitious matrix composition 28 comprises water, silica sand and cement. Silica sands can be, for example, blended quartzitic silica. Silica sands and blended quartzitic silica are available in several colors including light or white tones and darker colors. Preferably, when the decorative cementitious matrix blend is not required to be white or light color in tone, the cement is Type V Portland cement or equivalent cement having low permeability. The low permeability is desirable because it is more resistant to sulfates in the soil, salty sea breezes, and other concrete-detrimental salts.
However, when the decorative cementitious matrix blend is required to be white or light color in tone, a white Portland cement is used since Type V Portland cement has a darker appearance. To maintain the light color of the decorative cementitious matrix blend when using white Portland cements, any fly ash present in the formulation should be replaced by an additional amount or percent of white Portland cement. As stated at page 17 of Kosmatka and Panarese, xe2x80x9cDesign and Control Of Concrete Mixturesxe2x80x9d, 13th Edition, Portland Cement Association, 1994, 4th printing, white Portland cement is a true Portland cement that differs from gray cement chiefly in color. It is made to conform to the specifications of ASTM C150, usually Type I or Type III, but the manufacturing process is controlled so that the finished product will be white. White Portland cement is made from selected raw materials containing negligible amounts of iron and magnesium oxides, i.e. the substances that give cement its gray color; see TABLE 1. Its use is recommended whenever white or colored concrete is desired. Usually, white Portland cement is equivalent in strength to Type I or Type III Portland cement.
Chemical and compound composition and fineness of some typical Portland cements can be found at page 21 of the above-mentioned xe2x80x9cDesign and Control Of Concrete Mixturesxe2x80x9d publication and also in Kirk and Othmer, eds., xe2x80x9cCement,xe2x80x9d Encyclopedia of Chemical Technology, 3rd ed., vol. 5, John Wiley and Sons, Inc., New York, 1979, pages 163-193, and which is also shown in TABLE 1 for Portland cement Types I, III and white. Variations in the this data will occur from one cement source to another, however, such variations are still considered to fall within the specification of ASTM C150, which is hereby entirely incorporated herein by reference. These references should be consulted for more in-depth explanation of the effect of such parameters on concrete.
In one embodiment the cementitious composition comprises silica fume for improving strength and securing the decorate aggregate. Condensed silica fume is a by-product from silicon and ferrosilicon industries, where these metals are produced in submerged electric arc furnaces. The fume from these processes forms minute, glassy, spherical particles referred to as microsilica or silica fume that is considered a waste product of limited value. Microsilica is an extremely fine particulate, with average diameters 100 times finer than cement particles and is almost pure silicon dioxide or SiO2. Most condensed silica fume has an average size of about 0.15 micrometers, while a typical Portland cement has an average particle size of 15 micrometers.
Since silica fume speeds up the rate of cure effective retardants can be added if needed to allow more time for the resultant slurry to be worked. For example a small amount of fly ash Class C is added as a retardant where the decorative aggregate is xc2xc inch or larger and where the resulting decorative surface is not required to be white or light color in tone. As disclosed by ASTM designation C618-01, published September 2001 and in U.S. Pat. Nos. 4,992,102 and 5,266,111 and 5,520,730, Class C fly ash is normally produced from lignite or subbituminous coal. This class of fly ash, in addition to having pozzolanic properties also has some cementitious properties. Some Class C fly ash may contain lime contents higher than 10%. Class C and F fly ash is characterized by American Society of Testing Materials (ASTM) Standard C618 that sets forth the following chemical (oxide basis) and physical requirements:
Class F fly ash normally produced from burning anthracite or bituminous coal has pozzolanic properties. The reference to xe2x80x9cpozzolanic propertiesxe2x80x9d refers to the capability of certain mixtures that are not in themselves cementitious of undergoing a cementitious reaction when mixed with lime in the presence of water. Class C fly ash possesses direct cementitious properties as well as pozzolanic properties. U.S. Pat. Nos. 4,992,102 and 5,266,111 and 5,520,730, disclose how to produce synthetic Class C fly ash from Class F fly ash and cement kiln dust and are hereby entirely incorporated herein by reference. Synthetic Class C fly ash and other equivalent materials thereof can be used in this invention. Accordingly, by the expression xe2x80x9cClass C-likexe2x80x9d fly ash as used herein is meant to include Class C fly ash, synthetic Class C fly ash and fly ash that has both pozzolanic properties and cementitious properties equivalent to Class C fly ash. Class F fly ash without CKD can also be used in place of the above-mentioned synthetic Class C fly ash, however it would not be as effective.
Superplasticizers can also be added to the decorative cementitious matrix blend to make a flowing concrete and/or to reduce water content to gain higher early strengths, for example polymer containing WRDA(copyright)-19 brand superplasticizer and chemical dispersants containing DARACEM(copyright)-100 brand superplasticizer of W. R. Grace and Co.
In one embodiment, the process further comprising leaving a rough, unsmoothed and wet surface 30 on the freshly poured cementitious base, and pouring the decorative aggregate-containing cementitious slurry 24 on the rough, unsmoothed and wet surface 30.
Non-limiting examples of decorative aggregate 26 are natural hard materials, synthetic hard materials, and mixtures thereof that form decorative aggregate-containing cementitious surfaces. Other non-limiting examples are decorative aggregate is selected from the group consisting of ceramic, ceramic chips, marble, marble chips, granite, granite chips, sea shells, sea shells chips, sea crustacean remains, fragments of sea crustacean remains, glass, glass chips, natural aggregates selected for their color, natural aggregates selected for their texture, natural aggregates selected for their attractiveness and strength, and mixtures thereof.
In one embodiment of this invention, the decorative aggregate has a size between about {fraction (1/32)} inch and about xc2xd inch. In another embodiment, the decorative aggregate has a size between about {fraction (1/32)} inch and about xe2x85x9c inch. Sizes of the decorative aggregate when referred herein mean the mean diameter of the decorative aggregate unless otherwise specified.
In one embodiment, the process further comprising removing detrimental material, including dirt and grit, from the decorative aggregate before preparing the decorative aggregate-containing cementitious slurry.
The process further comprises pouring an amount of the decorative aggregate-containing cementitious slurry 24 on the freshly poured cementitious base within a period of time after forming the freshly poured cementitious base, effective for forming a monolithic structure, when simultaneously cured with the freshly poured cementitious base. The amount of the decorative aggregate-containing cementitious slurry 24 must be sufficient to produce a decorative aggregate-containing cementitious layer having a thickness 31 operable, when cured, for permanently securing the decorative aggregate therein. Furthermore, at least a portion of the decorative aggregate forms a portion of the exposed surface of the decorative aggregate-containing cementitious layer.
In one embodiment, the period of time for pouring the decorative aggregate-containing cementitious slurry on the freshly poured cementitious base between about one minute and no more than about 3 hours from the time of completing the pouring of the freshly poured cementitious base. In another embodiment, the period of time for pouring the decorative aggregate-containing cementitious slurry on the freshly poured cementitious base is immediately after, or as soon as possible after, completing the pouring of the freshly poured cementitious base.
The one embodiment, the process further comprises adding and mixing a colorant in the decorative aggregate-containing cementitious slurry before pouring the slurry on the freshly poured cementitious base.
The process further comprises simultaneously curing (1) the decorative aggregate-containing cementitious slurry poured on the freshly poured cementitious base, with (2) the freshly poured cementitious base, for a period of time effective for producing a monolithic architectural cementitious structure 32 having a decorative aggregate-containing cementitious surface 34, as represented in FIG. 3, in which the boundary 36 seen in FIG. 2, between the earlier poured cementitious base 23 and the decorative aggregate-containing cementitious slurry 24 has vanished due to the cementitious reaction resulting from the curing process thereby producing a monolithic structure.
The period of time for a 75% cure of the decorative aggregate-containing cementitious slurry and the freshly poured cementitious base is about 7 days under normal conditions.
In one embodiment, in about 30 minutes after pouring the decorative aggregate-containing cementitious slurry, the process further comprises leveling the decorative aggregate-containing cementitious surface. In another embodiment, in about 30 minutes after leveling the decorative aggregate-containing cementitious surface, the process further comprises bullfloating the decorative aggregate-containing cementitious surface and forming a smoothed surface. In still another embodiment, in about 60 minutes after bullfloating the decorative aggregate-containing cementitious surface and forming the smoothed surface, the process further comprises troweling and sponging the decorative aggregate-containing cementitious surface to further enhancing the appearance thereof.
In a further embodiment, the process comprises, after about 7 days of curing the decorative aggregate-containing cementitious slurry with the freshly poured cementitious base, washing the decorative aggregate-containing cementitious surface with a dilute acid to brighten exposed decorative aggregate.
In another embodiment, after washing the decorative aggregate-containing cementitious surface with a dilute acid to brighten exposed decorative aggregate, the process further comprises testing the surface to determine if the dilute acid has been neutralized, and after the testing shows that the surface has been neutralized, sealing the surface with a sealant effective for protecting the surface. The dilute acid will become neutralized in about 2 to about 8 days after the dilute acid washing.
In one embodiment, the thickness 31 of the decorative aggregate-containing cementitious layer is at least about {fraction (1/16)} inch. In another embodiment, the monolithic architectural cementitious structure has a thickness 38 of at least about 3 ⅝ inches, i.e. nominally 4 inches.
There is also provided by the principles of this invention decorative cementitious matrix blends comprising blended quartzitic silica, Portland cement, and silica fume, which when mixed with an effective amount of water, followed by mixing with a predetermined amount of decorative aggregate can be used to form the decorative aggregate-containing surfaces of this invention. In one embodiment, the decorative cementitious matrix blend also comprises a small amount Class C-like fly ash as a curing retardant. Minor amounts of other accelerants, retardants, and/or hardeners can, of course, be used if desired.
In one embodiment, the effective amount of water that is added to the decorative cementitious matrix blend and of decorative aggregate forms a slurry having sufficient fluidity that the slurry can be worked through the last troweling step of producing the smooth decorative aggregate-containing surface. However, said amount of water shall be limited so that it does not produce surface shrinkage cracking the first day of curing, nor premature surface wearing thereafter.
In one embodiment, the effective amount of water that is added to the decorative cementitious matrix blend and of decorative aggregate forms a slurry having a slump between about 3 inches and 5 inches.
In one embodiment, the dry components comprise about 60 parts of decorative cementitious matrix blend and about 40 parts of decorative aggregate, which is then slurried with water to produce the decorative aggregate-containing cementitious slurry.
In one embodiment, the decorative cementitious matrix blend contains between about 20% and about 35% of Portland cement or equivalent cement thereto, preferably between about 22% and about 33% , and especially preferably between about 25% and about 32%.
In one embodiment, the decorative cementitious matrix blend contains between about 50% and about 79% blended quartzitic silica or an equivalent silica thereto, preferably between about 35% and 45%, and especially preferably about 40%.
In another embodiment, the blended quartzitic silica, when graded using Standard Sieve Sizes 16, 20, 30 and 60 for such analyses, is about 25% Standard sieve size 16, about 37% Standard sieve size 20, about 25% Standard sieve size 30, and about 13% Standard sieve size 60.
In another embodiment, the decorative cementitious matrix blend contains silica fume up to about 5%, and preferably between about 0.1% and about 4%, and especially preferably between about 1.5% and about 3.5% as a strengthening and binding agent.
In still another embodiments that include decorative aggregates larger that about xc2xc inch and that are not used to form white or light colored surfaces, the decorative cementitious matrix blend contains Class C-like fly ash up to about 8%, and preferably between about 5% and about 7%, as a retardant.
In one embodiment, the ratio of cement to blended quartzitic silica is between about {fraction (10/40)} (25%) and about {fraction (25/40)} (63%), preferably between about {fraction (12/40)} (30%) and about {fraction (22/40)} (55%), and especially preferably between about {fraction (15/40)} (37%) and about {fraction (20/40)} (50%).
In one embodiment, the ratio of silica fume to blended quartzitic silica is up to about {fraction (4/40)} (10%), preferably between about {fraction (0.5/40)} (1%) and about {fraction (2/40)} (5%), and especially preferably between about {fraction (1/40)} (2.5%) and about {fraction (2/40)} (5%).
In one embodiment, the ratio of decorative aggregate to decorative cementitious matrix blend is between about {fraction (20/60)} (33%) and about {fraction (50/60)} (83%), preferably between about {fraction (35/60)} (58%) and about {fraction (45/60)} (75%), and especially preferably about {fraction (40/60)} (67%).
In one embodiment, the ratio of cement to decorative aggregate is between about {fraction (10/40)} (25%) and about {fraction (30/40)} (75%), preferably between about {fraction (12/40)} (30%) and about {fraction (25/40)} (63%), and especially preferably between about {fraction (15/40)} (37%) and about {fraction (20/40)} (50%).
In one embodiment, the ratio of silica fume to decorative aggregate is up to about {fraction (4/40)} (10%), preferably between about {fraction (1/100)} (1%) and about {fraction (3/40)} (7.5%), and especially-preferably between about {fraction (1/40)} (2.5%) and about {fraction (2/40)} (5%).
In one embodiment, the size of the decorative aggregate is no greater about xc2xd inch, preferably no greater than about xe2x85x9c inch, and especially preferably no greater than about xc2xc inch.
In another embodiment, the size of the decorative aggregate is between about {fraction (1/32)} inch and about xc2xd inch, preferably between about {fraction (1/32)} inch and about xe2x85x9c inch, and especially preferably between about {fraction (1/32)} inch and about xc2xc inch.